How to get posebone global location
This is a bit of a duplicate of this question, but just to complete the picture, to get the global location of your pose bone, you need to multiply the bone's location by the armature and the bone's transform matrices (sounds complicated, but is actually simple):

p = bpy.context.active_pose_bone  # Our pose bone
o = bpy.context.object            # Our armature object
global_location = o.matrix_world * p.matrix * p.location